Sentry, Dynatrace, Lighstep, Jaeger, Zipkin, Tempo, New Relic, AWS X-Ray, Datadog, … - I wouldn’t use any vendor specific agent anymore. There is Open Telemetry standard for traces and you can export traces at the end to your favorite backend
So opentelemetry-java-instrumentation (which is running as Java agent - so no need to touch Keycloak source code, just config change) → OTEL collector with sentry exporter → Sentry. And you can change your tracing backend in the future anytime - again only exporter config change in the OTEL collector config.